1. Field of the Invention
Implementations of various technologies described herein generally relate to methods and systems for hydraulic fracturing operations. Implementations of various technologies described herein are also directed to determining characteristics of a subterranean body using pressure data and seismic data.
2. Description of the Related Art
The following descriptions and examples are not admitted to be prior art by virtue of their inclusion within this section.
Active Seismic Monitoring of Fracturing Operations
In the recovery of hydrocarbons from subterranean formations it is common practice, particularly in formations of low permeability, to fracture the hydrocarbon-bearing formation to provide flow channels. These flow channels facilitate movement of the hydrocarbons to the well bore so that the hydrocarbons may be pumped from the well.
In such fracturing operations, a fracturing fluid is hydraulically injected into a well bore penetrating the subterranean formation and is forced against the formation strata by pressure. The formation strata or rock is forced to crack and fracture, and a proppant is placed in the fracture by movement of a viscous-fluid containing proppant into the crack in the rock. The resulting fracture, with proppant in place, provides improved flow of the recoverable fluid, i.e., oil, gas or water, into the well bore.
Fracturing fluids customarily comprise a thickened or gelled aqueous solution which has suspended therein “proppant” particles that are substantially insoluble in the fluids of the formation. Proppant particles carried by the fracturing fluid remain in the fracture created, thus propping open the fracture when the fracturing pressure is released and the well is put into production. Suitable proppant materials include sand, walnut shells, sintered bauxite, or similar materials. The “propped” fracture provides a larger flow channel to the well bore through which an increased quantity of hydrocarbons can flow, thereby increasing the production rate of a well.
A problem common to many hydraulic fracturing operations is the loss of fracturing fluid into the porous matrix of the formation. Fracturing fluid loss is a major problem. Hundreds of thousands (or even millions) of gallons of fracturing fluid must be pumped down the well bore to fracture such wells, and pumping such large quantities of fluid is very costly. The lost fluid also causes problems with the fracturing operation. For example, the undesirable loss of fluid into the formation limits the fracture size and geometry which can be created during the hydraulic fracturing pressure pumping operation. Thus, the total volume of the fracture, or crack, is limited by the lost fluid volume that is lost into the rock, because such lost fluid is unavailable to apply volume and pressure to the rock face.
Determining Characteristics of a Subterranean Body Using Pressure Data and Seismic Data
Well testing is commonly performed to measure data associated with a formation or reservoir surrounding a well. Well testing involves lowering a testing tool that includes one or more sensors into the well, with the one or more sensors taking one or more of the following measurements: pressure measurements, temperature measurements, fluid type measurements, flow quantity measurements, and so forth. Well testing can be useful for determining properties of a formation or reservoir that surrounds the well. For example, pressure testing can be performed, where formation/reservoir pressure responses to pressure transients are recorded and then interpreted to determine implied reservoir and flow characteristics. However, due to the one-dimensional aspect of pressure, pressure testing provides relatively limited data. Consequently, a detailed spatial description of characteristics of a formation or reservoir typically cannot be obtained using pressure testing by itself.